fix(chart): curves in graph not synchronized on display

[lpinsivy]

Description

Since Centreon 19.10.0 RRDCacheD configuration is no more global but per Centreon RRD broker configuration.

Type of change

• Patch fixing an issue (non-breaking change)
• New functionality (non-breaking change)
• Breaking change (patch or feature) that might cause side effects breaking part of the Software
• Updating documentation (missing information, typo...)

Target serie

• 2.8.x
• 18.10.x
• 19.04.x
• 19.10.x (master)

How this pull request can be tested ?

• On a Centreon 19.04.0 enable RRDCacheD using PR fix(doc): update FAQ to install RRDCacheD on el7 #6955
• Update to Centreon 19.10.0
• Wait 1h
• Try to display a chart with 2 curves (traffic for example)
• Both curves should be synchronized and displayed

Checklist

Community contributors & Centreon team

• I followed the coding style guidelines provided by Centreon
• I have commented my code, especially new classes, functions or any legacy code modified. (docblock)
• I have commented my code, especially hard-to-understand areas of the PR.
• I have made corresponding changes to the documentation.
• I have rebased my development branch on the base branch (master, maintenance).

Centreon team only

• I have made sure that the unit tests related to the story are successful.
• I have made sure that unit tests cover 80% of the code written for the story.
• I have made sure that acceptance tests related to the story are successful (local and CI)